Tag Archives: Rechargeable Batteries

Autopsy Report: Sony ICF-SW100s

WARNING: due to the graphic nature of these photos, those radio enthusiasts who love the Sony ICF-SW100 may want to look away. Parental Discretion is advised.

Guest Post by Troy Riedel

Some of you may remember my recent lamenting regarding the unexpected loss of my beloved Sony ICF-SW100 posted on this blog. The Medical Examiner opened the radio’s chassis last week. The manner of death is rather obvious, but what caused it?  Before I reveal my research, allow me to quicky remind you of the context to the situation.

Due to a medical emergency, I “deployed” for two months to tend a remote farm (one of the few benefits was being able to drive a tractor – a kid from my generation grew-up dreaming of piloting heavy construction equipment and farm implements). I traveled there with two shortwave portables: the Sony ICF-SW100s and the XHDATA D-808. After a long day of work, shortwave radio was my only mode of relaxation during my extended period of solitude.

I had always used Eneloop nickel metal hydride (NiMH or Ni-MH) rechargeable batteries in my SW100. I’m not a physics nor a chemistry major (the closest knowledge I have is enough atmospheric physics to have once been a moderately successful synoptic weather forecaster & aviation weather briefer in the military). As such, my education doesn’t directly correlate so I offer an advance apology for my overly simplistic and layperson synopsis of the specific cause & manner of death of my SW100.

I think we all know that a battery is “energy stored inside of a small container”. And energy is heat – measured by random motion (random motion is directly proportional to heat meaning as motion increases or decreases, the heat generated by the motion will do the same).

NiMH & Lithium battery cells have an alkaline electrolyte, usually potassium hydroxide (potash). The electrolyte serves as the catalyst to make a battery conductive by promoting the movement of ions from the cathode to the anode on charge and in reverse on discharge. The electrolyte is sensitive as it has to be to promote charging & to generate power. And the heat that’s produced by the battery can be dangerous because as we previously discussed, a battery is a “closed” container that stores energy … and if we think about it, so is a bomb, right?

Well, the term closed is slightly misleading and not 100% correct. A rechargeable household battery has a vent which acts as an exhaust. This vent allows excess heat to escape. If you Google image search “NiMH battery anatomy”, there are two ways to vent heat. On Panasonic Eneloops and most commercial household batteries, the vent is the rubber puck (disk) under the positive button tab. This disk seals the internals (thus the term “closed”) while also permitting excess heat to [generally] safely vent. Some manufacturers actually have multiple exhaust openings (holes) around the button top that act as vents. Regardless of how it’s done, these batteries do have an exhaust or venting system.

To summarize thus far, rechargeable batteries vent excess heat (whether generated during use or during charging) from the top of the battery. Venting heat during charging is critical because as well all know, one does not want to overheat batteries during (re)charging. This is why everyone should use a smart charger.  A smart charger is one that monitors the energy level of the battery and shuts-off when it reaches capacity (I learned that capacity is defined differently by different manufacturers but all seem to shut-off somewhere at 90% or greater). I remember the portables that were released maybe 10-15 years ago that introduced charging inside the radio. The very early models were not smart, the user had to either program how many hours you wished to charge the battery/batteries or the radio itself was programmed to charge for x-amount of hours regardless of whether the batteries needed to be charged for that long (you could very easily continue charging for hours after the battery attained 100% capacity – a very dangerous situation for your valuable radio!). Thankfully most newer radios, except the inexpensive “no-frills” radios, have smart changing technology. Regardless, I have never been a fan of using my radio to charge batteries as I’ve always felt this is too dangerous because the process produces heat and I do not want [excess] heat generated (or vented) inside of my radio!

There are typically more shipping restrictions, more transportation restrictions with Lithium batteries than there are for NiMH batteries (I’m sure most people have noticed shipping restrictions when buying electronics regarding the shipment of Lithium batteries – and if shipment is allowed, it’ll cost more to ship because Lithium batteries cannot be shipped via all modes). Lithium (3.7v) & NiMH (1.2v) batteries are essentially the same technology, except Lithium generates more “power” aka “more heat” (3x the voltage) and are thus much more sensitive to heat (including environmental heat) .

In doing my research, I found a slight conflict regarding the stability of NiMH batteries in storage. Some manufacturers warn that NiMH batteries should not be stored in temperatures over 30C (86F) while others list 40C (104F) as the threshold. What happens above this threshold? The electrolyte catalyst is activated, and the battery will generate its own heat (heat that must be vented).

At this point, I’m sure you can see where this is going. I had two NiMH batteries inside of my SW100. The two stacked batteries increased the inherent risk (in a worst-case situation, two batteries would create & release/vent more heat than a single battery). I was in a hot environment, I lacked air conditioning for most of the time, and I had a long drive of nearly 300-miles to/from my location at the start & the end of the two months I was there. My SW100 was apparently put into peril when it encountered environmental [ambient] temperatures that exceeded the Eneloops threshold (30C? 40C?). And this caused the NiMH Eneloops to heat-up beyond normal, vent the excess heat, and thus “melt” part of the PCB and the back case of the SW100.

This did not happen during normal storage of my radio in my temperature-controlled house, but rather it happened in the adverse environment I temporarily subjected the radio to.


Yes, I know … think what you want (but please don’t say it). User error.  I should have known better.  It was my fault. It was dumb. Yes, yes, yes & yes answer those four statements. I know, I know …

There are three positives to this:

(1) I learned a painful albeit valuable lesson;

(2) Maybe others can learn from my folly; and

(3) Parts to maintain these classics must be salvaged. I donated my radio (including the AC adapter) – it’s not a total loss and it still has value as a “parts radio”. My SW100 is now in the hands of a skilled, master technician who might be able to save the life of another (or multiple) SW100 radio(s).

My loss just might be someone else’s gain? I take comfort that my radio may live on (as an organ donor) to potentially provide years of enjoyment for someone else.

Postscript re: my initial post:

I have picked-up a few of my other shortwave radios since my initial post (PL-390, PL-880, XHDATA D-808, Satellit 750) & I have started listening again.

And I did have surgery a couple of weeks ago for the physical injury I sustained while tending the farm (my ICF-SW100 wasn’t the only casualty during this period of time). After a frustrating 2+ weeks, I’m starting to make progress with my physical healing. And now that I have a definitive answer on the manner & cause of death of my SW100, I’m psychologically healing from that as well.

UPDATE after my initial post:

I neglected to make the following statement: one can debate whether the excessive heat being vented caused the PCB & case to melt, or if the vent(s) in one or both batteries failed, or if the battery heated-up too quickly & too much for it to safely vent?  The only thing I do know: the batteries exhibit no physical damage or defect so the exact mechanism of the the excessive heat will remain unknown.

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Troy finds Tenergy Centura low self-discharge batteries a great value

Many thanks to SWLing Post contributor, Troy Riedel, who recently shared his observations about low self-discharge batteries with me. He has kindly allowed me to post his message here on the SWLing Post. Troy notes:

I’ve lauded Tenergy rechargeable NiMH batteries and I wanted to share something with you.

Mighty Bright Navigation Light

I have a box of Mighty Bright combination Red & White LEDs that I use for astronomy (they’re a clip-on light used by pilots and also marketed for use in the automobile – they hold three AAAs).

Approx. 18-months ago I put fully charged Rayovac, Energizer, Eneloop & Tenergy Centura Low Self-Discharge batteries in them.

Last night I pulled them out.

Rayovac: 0% charge.
Energizer: 0% charge
Tenergy Centura LSD & Eneloop: both averaged ~ 70% of a charge … (6 batteries in two lights) … though some of the Eneloops had a slightly higher charge (maybe 2 – 5% higher), most of the batteries were virtually indistinguishable.

You can buy 8 Tenergy for $9.99 while 8 Eneloop cost $17.99.

If cost were not an issue I’d still go with Eneloop (a longer track record), but the Tenergy is a worthy – no, very worthy – value vs. performance choice.

Panasonic Eneloop batteries

Thanks for sharing your real-world feedback, Troy.

I’m a big believer in low self-discharge rechargeable batteries. Indeed, I’ve almost replaced all of our “legacy” (meaning not low self-discarge) NiMH AA and AAA batteries with Eneloop cells.

Eneloops are pretty pricey, though, and the costs add up if you have a lot of devices that require batteries. As you might imagine, portable radios demand a steady supply of AA batteries at SWLing Post HQ.

I’ve been very pleased with my Eneloop batteries and, frankly, haven’t switched brands because of the terrible luck I’ve had with “legacy” rechargeables in the past. I’ve purchased so many that worked wonderfully for a few months then began to lose their capacity even though I employ an intelligent charger that properly breaks-in and cycles them.

I do believe I’ll add some Tenergy AA and AAA batteries in the mix now–especially for non-radio applications like lighting, remotes, clocks, and other consumer electronics.

Click here to check out Tenergy batteries and click here to check out Eneloop batteries at Amazon.com (affiliate links support the SWLing Post).

What are your observations?

Have you used Tenergy and Eneloop batteries? What about other brands?  Please share your thoughts by leaving a comment on this post.

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Adid finds affordable AA to D cell adapters

Many thanks to SWLing Post contributor, Adid, who writes:

I just ran across this adapter


I don’t know if D type is still available everywhere, but not here in Israel.

So this can be very handy if one needs to revive a D type device occasionally.

Thanks for the tip, Adid! This could be a very helpful product for radio enthusiasts who have some of the classic solid state receivers of the 1970s and 80s, like the Panny RF-2200.

It’s not difficult in the States to find D cells but rechargeables are not as commonplace and are quite pricey, often requiring their own dedicated D cell chargers. Since I almost exclusively use rechargeable batteries, I have two of these Eneloop “power packs” (affiliate link) that have AA to D cell adapters inside. Of course, your option is much less expensive and should yield better overall capacity when using standard alkaline cells.

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More info about Eneloops and avoiding counterfeits

Following our post yesterday regarding Eneloop rechargeable cells, SWLing Post contribtors Guy Atkins and Ivan Cholakov both warned of numerous fake and counterfeit batteries available from sellers on eBay and elsewhere. Ivan notes:

Please be aware Eneloop batteries are widely copied and there are many many fakes out there. You should only buy them from a reputable source.

Thank you for that warning, Ivan!

Guy also comments:

I use Eneloop Pro AA batteries in small portables. The newest version of the “Pro” comes in a 2500 maH size and retains 85% of the charge for one year. The downsize is that this model is “only” good for 500 recharges. A useful comparison chart is here: https://en.wikipedia.org/wiki/Eneloop

[…]Here is a FAR more comprehensive page of Eneloop model & version comparisons, charts, FAQs, tips, warnings, etc.: https://eneloop101.com/batteries/complete-lineup/. This web site also contains warnings about Ebay fake Eneloops, and other useful details…probably more than most people want to know but if you want to make the most informed choice, check it out!

Many thanks to both of you for sharing. I agree that purchasing Eneloops from a reputable seller is incredibly important. For one thing, if you plan to invest in Eneloops, there is no rationale to buy something sub-standard. Additionally, I do worry about counterfeit cells having an unstable chemistry which could result in overheating or fire.

Click here to read our original Eneloop article with links to reputable sellers.

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Marcus recommends Panasonic Eneloop rechargeable cells

Many thanks to SWLing Post contributor, Marcus Keulertz, who writes:

I use these special rechargeable batteries [Panasonic Eneloop cells] for almost everything especially in household appliances and think what else?

In my energy hungry portable radios and active Loop Antennas. They are reliable power sources, especially in the cold weather period right now. They are quite expensive but worth to have them with you, when travelling.

Thanks for sharing, Marcus!  Like you, I almost exclusively use Eneloop cells in my portable shortwave radios (save when I’m doing an evaluation and use fresh alkalines for comparison consistency).  I even use Eneloops in my Elecraft KX3 transceiver. They’re brilliant! For daily use, Eneloops are simply invaluable as they hold a charge much longer than standard AA cells.

We’ve purchased three of the Eneloop starter packs in the past–two via Amazon.com (affiliate link) and one via Costco (who no longer sells them). I’ve also purchased these multi-packs of AA cells since they’re the most widely used battery in our household. The great thing about the starter packs is that they include AAA cells and D and C cell adapters.

True: Eneloops aren’t cheap, but I think they’re worth the price. Once I invested in them, I gave my other rechargeable cells away.

Thanks for your comments, Marcus.

Click here to shop Eneloops at Amazon.com (affiliate link). Also shop Walmart and B&H Photo.

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Steve searches for a USB-powered battery charger for solar recharging

Many thanks to SWLing Post contributor, Steven Crawford, who writes with the following inquiry:

[I’m searching for] good quality USB powered battery chargers for AA and D size rechargeable batteries.

Wall outlet chargers are common but quality USB powered battery chargers appear much less common…less common than the packable solar panels with USB ports such as Anker’s, that could be used to power them. Ideally the charger should handle Nicad’s, NIMH and Ii-on but have standardized on AA, AA + D adapter sleeves, and D batteries for my storm supplies.

If I understand correctly, you’re searching for a good qualityUSB-powered battery charger that supports multiple battery chemistries (nickel-cadmium, NIMH and lithium ion) so you can recharge AA, AAA and D batteries with a portable solar panel.

I’m hoping SWLing Post readers can offer some suggestions.

I’ve also looked into this type of charger for both Ears To Our World and my own personal use when off-grid in the summer. I’ve never found one that truly supports all of the battery chemistries you mentioned. The one I’ve used (an EBL) works quite well, but only supports NiMH AA and AAA batteries. As you mentioned, you can use D cell sleeves with the AAs.

EBL makes a number of USB chargers that can be found by searching Amazon. This one–an EBL Quick Charger (affiliate link)–can recharge NiMH batteries within 40 minutes and I’ve personally used one. I’ve been pleased with EBL batteries as well.

I never use nickel cadmium rechargeable batteries at this point, so really don’t know what’s available on the market.

I have found that there are a number of USB-powered lithium battery chargers, but typically for specific lithium cell configurations like 18650, 16340, 14500, 26650, etc. Some of these inexpensive chargers have magnetic contacts that can fit almost any battery type and on Amazon and eBay they claim to recharge multiple battery chemistries, but frankly I’m quite skeptical. These $9 devices don’t seem to have a way of detecting battery chemistry, thus I’m not sure how they would adjust the charging cycle accordingly. Perhaps I’m incorrect in this assumption?

Other than using Powerfilm solar NiMH battery chargers (I can recommend these) which are incorporated in their folding panels, I’ve never charged batteries directly from a solar panel. Typically I have a 9ah or larger 12V battery floating between the PV panel and the charger.

I’ve found that using a 12VDC charger–like this–that’s pulling power from a 12V battery is simply a little more efficient, faster and reliable than charging directly from a small PV panel. Since I always have 12V batteries on hand when off grid, it’s a simple solution for for my system.

Post readers: do you have any USB-powered battery charging suggestions for Steven? Please comment!

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Anil’s hack: Using a smart phone battery bank to power portable receivers

Many thanks to SWLing Post contributor, Anil Raj, who writes:

I wanted to share a small but useful hack with your readers.

I use a common garden variety smartphone “Powerbank” 10,000 mAH Li Ion pack to power my Sony 7600GR which is perfectly happy with the 5V which the pack supplies. [See photo above.] I see no reason why this won’t work with other radios which require a 6V supply.

As you can imagine, the setup typically lasts for many weeks of extended daily listening and recharges in a jiffy. However, one needs to sacrifice a USB cable by soldering a DC plug at the other end. Haven’t bought AA batteries in a long time…

Thank you, Anil! What a simple but useful hack. The best part is, battery packs/banks are  very inexpensive these days and, I for one, have a number of USB cables I could sacrifice for the job!

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